The present invention relates to a process and an arrangement for the treatment of objects, in particular for sterilization, comprising at least one chamber for the joint take-up of at least two objects to be treated, also comprising a minimum of one sealing element arranged to the opening of the chamber, which sealing element is arranged in a moveable way in the arrangement for the purposes of opening and closing the opening, whereby the chamber can be closed by means of the closing element in a vacuum-tight way, and whereby the closing element is arranged in the closed state to the chamber in such a way that no relative movement takes place between the closing element and the chamber.
The present invention relates further to a process for sterilizing a minimum of two objects to be sterilized in a joint chamber, which can be closed by means of a minimum of one closing element in a vacuum-tight way, whereby no relative movement takes place between the closing element and the chamber in the closed state.
Attention is brought to the fact that the definition “vacuum-tight” is not to be taken literally, but rather is defined on the basis of the process carried out in the chamber. The demands made on the seals are hereby essentially dependent on the required pressure in the chamber as well as on the level of a tolerable leakage of air.
An arrangement of the above mentioned type is prior art in German published patent application DE 199 16 478 A1. A round runner for the plasma sterilization of receptacles is described. The round runner comprises for example 50 chambers for taking up one receptacle each. The quantity produced by the round runner lies in the range of 20,000 receptacles per hour. Each chamber fixed to the round runner comprises a releasable base plate, which can be moved downwards. In order to load the chamber, a receptacle is placed on the released base plate, which is then moved upwards again until the plate touches the remaining chamber walls and the chamber is sealed. During the rotation of the round runner, the base plate moves together with the chamber, so that no relative movement takes place between the closing element and the chamber. The base plate is moved downwards again to open the chamber only at the end of the treating process, so that the receptacle can be removed.
Arrangements of this type are not only applied for plasma sterilization, but also for a process of the above mentioned type. A process of this type is known in German published patent application DE 101 12 971 A1. The disclosed process permits an effective sterilization of objects in the round runner, without a plasma having to be ignited. The effectiveness can be hereby improved.
An arrangement of this type has in particular the advantage that a very high production of objects is achievable due to the continuous way the machine operates, for example in the range of 30,000 objects per hour. Disadvantageous hereby is, however, that a very large number of chambers for taking up the objects have to be provided. The standard number of chambers is between 50 and 100. A set of valves is necessary for each chamber, in order to connect this chamber with the various supply and evacuation devices for the individual procedural steps. The entire arrangement requires a great amount of installation space, as the diameter of the round runner is extremely large due to the large number of chambers.
In the past, attempts have been made to optimize such arrangements by applying a number of objects, for example two or three, simultaneously in each chamber of the round runner. This leads to a light reduction in the number of chambers while maintaining the production performance, but the feed and removal of the objects to be treated cannot take place continuously. In an installation which transports the objects continuously, the removal of two objects simultaneously causes a discontinuity, which must be then be compensated for by a subsequent holding time. Because of this caused discontinuity, a discontinuous procedure of this type is fundamentally disadvantageous.
It is an object of the present invention, while maintaining the advantage of the continuous modus of operation, to reduce the number of necessary chambers and thus to simplify the arrangement and reduce the required installation space.
This object has been achieved in accordance with the present invention in that a minimum of two objects to be treated are inserted into the chamber one after the other, and in that the opening is essentially continuously closable by means of at least one closing element.
The feature of the essentially continuous closing of the opening is hereby to be understood in that the closing can take place in a phase comprising a number of steps, or continuously without steps. For this purpose, a number of rigid closing elements for a step-by-step closing of the opening in a number of stages can be arranged to the opening of the chamber. It can also be provided that a flexible closing element for continuous closing of the opening is arranged to the opening of the chamber.
The object of the present invention has been achieved in regard to the process in that the minimum two objects are inserted to the chamber one after the other, and in that the chamber is partly closed after the insertion of each object, and in that the chamber is closed in a vacuum-tight way and evacuated after the last object is inserted, and in that the vapour mix of gaseous hydrogen peroxide and gaseous water flows into the chamber in less than 8 seconds (in the following shortened to s), so that a condensation layer forms on all the accessible surfaces of the objects and the chamber, which condensation layer sterilizes the surfaces, and in that a renewed evacuation of the chamber begins at latest three seconds after the formation of the condensation layer, whereby the pressure of the chamber is lowered below the vapour pressure of the hydrogen peroxide thus resulting in the removal of the condensation layer, and in that the chamber is flooded with a sterile gas, and in that the chamber is opened essentially continuously and the objects can thus be removed one after the other from the chamber.
The advantage is achieved hereby in that the number of chambers can be reduced to between one and ten, without compromising on the continuous production of approximately 20,000 to 40,000 objects per hour. As a result of the reduced number of chambers, the arrangement requires significantly less installation space. In addition the supply of low pressure and hydrogen peroxide vapour mix to the chamber is simplified. Although the arrangement operates continuously, all objects inserted into a joint chamber are simultaneously at the same procedural step with regard to the treating process being carried out.
It should be expressly stated at this point that the described arrangement is in particular suitable for the described sterilization process, but is by no means limited to this process. The arrangement is just as ideally suitable for a plasma sterilization or for coating objects with plasma. Particularly advantageous is the application of the arrangement for treating bottles or other receptacles to be filled.
It is advantageous when a number of objects to be treated are inserted one after the other in at least two chambers, whereby the chambers are arranged to a chamber wheel which is driveable at a constant circumferential speed. Depending on the process to be carried out in the arrangement, two or three or several more chambers can be arranged to the chamber wheel. For the described sterilization process, three evenly distributed chambers on the circumference of the chamber wheel are advantageous.
In international patent application WO 2006/010509 A2 an air lock comprising a number of chambers arranged to a chamber wheel for the conveying of objects into a large treatment chamber. The chambers of the chamber wheel are successively evacuated to the pressure level of the treatment chamber while the chamber wheel is rotating. In the case of this airlock, continuous opening of the chambers is provided as a basic feature. However, in the case of this air lock there is no movable closing element, which, in the closed state, does not exert a relative movement in relation to the chamber. Instead, the chamber wheel of the air lock is surrounded by a stationary housing wall, in which two openings for filling and emptying the chamber are arranged. The chambers of the chamber wheel are surrounded by sealing elements which slide along the housing wall. The chambers, rotating with the chamber wheel, execute a relative movement to the housing wall closing the chambers, whereby a high level of wear occurs. It is necessary to change the sealing elements often. Each chamber of the air lock can take up two objects, which are, however, inserted simultaneously and not one after the other.
For a plasma treatment process or for the above described sterilization process it is advantageous when the arrangement comprises at least one central pump station for evacuating the chambers of the chamber wheel, which is connectable to all chambers one after the other in timed sequence, whereby each central pump station is connected at any one time to a maximum of one chamber. The central pump station can thus be optimized to the chamber size and to the required vacuum. As a result of the connection of at most one chamber with the central pump station, the situation is avoided whereby the vacuum level in the chamber originally connected with the pump station is affected because a second chamber is connected up to the same pump station.
It is advantageous to adapt the number of the chambers arranged on the chamber wheel to the process being carried out. The circumferential speed of the chamber wheel should be advantageously so chosen that a circulation time for one revolution arises, which essentially corresponds to the product out of the number of chambers, multiplied by the time a chamber is connected with a central pump station during one revolution of the chamber wheel. This results in the at least one central pump station being loaded very consistently and functioning with a high efficiency.
For the described sterilization process it is advantageous when an evaporator for an aqueous hydrogen peroxide solution is arranged to each chamber of the arrangement, which evaporator is applied in particular to the chamber wheel. By means thereof, a predetermined amount of an aqueous hydrogen peroxide solution can be very simply totally evaporated for each chamber at the required point in time, and fed to the respective chamber without the need for a carrier gas flow. For the described sterilization process it is advantageous when a vapour mix comprising a hydrogen peroxide concentration of approximately 14 to 59 percent regarding weight, preferably approximately between 25 and 50 percent regarding weight, and in particular comprising a hydrogen peroxide concentration of between 30 and 35 percent regarding weight is fed into the chamber. Due to the complete vaporization of a pre-measured amount of an aqueous hydrogen peroxide solution, it is necessary that the applied aqueous hydrogen peroxide solution has the same hydrogen peroxide concentration which the vapour mix flowing into the chamber should have.
It is advantageous, that the vapour mix flows into the chamber in less than 4 s, in particular less than 2 s. As a result of the rapid flow of the vapour mix into the chamber, an abrupt, essentially adiabatic expansion of the vapour mix takes place, which leads to a high level of cooling of the vapour mix. The vapour mix is thus over-saturated, so that condensation takes place on all exposed surfaces of the objects and of the chamber. This condensation also takes place abruptly, so that the condensation layer is heated to a great degree by the released evaporation enthalpy, thus leading to an “activation” of the hydrogen peroxide. The sterilization of the surfaces thus takes place practically in the moment of condensation. The chamber is evacuated again directly after the condensation formation, and the condensation layer is removed by lowering the pressure in the chamber below that of the vapour pressure of the condensed hydrogen peroxide.
The pumping out of the condensation layer takes place without any significant acting time directly after condensation, so that the condensation layer, warmed by the evaporation enthalpy, does not cool down by means of heat conduction to the surfaces of the objects and of the chamber. It is advantageous that the evacuation for removing the condensation layer is completed within 20 s, in particular within 10 s, after the vapour mix begins flowing in. This can prevent an excessive heat conduction of the condensation layer to the surfaces, so that the condensation layer can be very easily evaporated during evacuation and drawn off. The pressure in the chamber during evacuation to remove the condensation layer is preferably lowered to below 5 hectopascal (shortened in the following to hPa). The given pressure value corresponds to the absolute pressure in the chamber. The pressure can advantageously be lowered to below 1 hPa, in particular to below 0.35 hPa. The lower the pressure in the chamber during removal of the condensation layer, the less rest amount of hydrogen peroxide remains on the surfaces of the objects. Too large a rest amount of hydrogen peroxide on the objects can be disadvantageous for the further application of the objects.